# Star-Star Connection in Three Phase Transformer - MCQs with Answers

## Star-Star Connection in Three Phase Transformer - MCQs with Answers

Q1. For the star-star connection of three phase transformer, the phase angle between the phase voltages and line voltages on both primary and secondary side is

a. 0 degree
b. 30 degree
c. 60 degree
d. 120 degree

Q2. While connecting three phase transformer in star-star connection, the terminals of secondaries are wrongly joined. Then the mutual phase angle and magnitude of line to line voltages of secondaries will

a. Equal to 120 degree and equal as before
b. Not equal to 120 degree and different
c. Equal to 120 degree and different
d. None of these

ANSWER: b. Not equal to 120 degree and different

Q3. For the parallel operation of three phase transformers, which among the following connection is not applicable?

a. Δ - Δ to Y - Y
b. Y - Δ to Δ - Y
c. Y - Y to Y - Y
d. None of these

Q4. Due to presence of third harmonic component in the star-star connection of three phase transformer, the frequency of the circuit component becomes

a. Three times of the circuit frequency
b. One third of the circuit frequency
c. Remains same
d. None of these

ANSWER: a. Three times of the circuit frequency

Q5. In star-star connection of three phase transformer, if VL is the line voltage and IL is the line current then phase voltage and phase current is given by

a. VL / √3 , IL
b. VL , IL
c. √3VL , IL / √3
d. VL, IL / √3

ANSWER: a. VL / √3 , IL

Q6. The phase shift in a star-star connected three phase transformer is

a. 0 degree
b. 30 degree
c. 60 degree
d. 120 degree